Compressor unloader



p 21, 937. A. A. KUCHER 2,093,811

COMPRES 5 OR UNLOADER Filed June 4, 1932 I5 Sheets-Sheet 1 p 2 1937- A. ,A. KUCHER 2,093,811

COMPRES SOR UN LOADER Filed June 4, 1952 3 Sheets-Sheet 2 Sept. 21, 1937. KUCHER 2,093,811

Filed June 4, 1932 5 Sheets-Sheet 3 Patented Sept. 21, 1937 UNITED STATES PATENT OFFICE 2,093,811 COMPRESSOR UNLOADER Application June 4, 1932, Serial No. 615,348

4 Claims.

This invention relates to compressors or pumps for compressing or pumping refrigerants or fluids.

It is among the objects of this invention to provide a device to enable a compressor or pump to start under a reduced load and in which the mechanism for accomplishing this purpose is of a simple nature, has few parts, and is capable of accomplishing the unloading of the compressor effectively and immediately, and, if desired, even' before the compressor has come to a full stop.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the'drawings:

Fig. 1', is a vertical cross-sectional view of a compressor or pump embodying features of my invention;

Fig. 2 is a top plan view, partly broken away, of a portion of the mechanism shown in Fig. 1, the parts being shown when the compressor has attained normal speed;

Fig. 3 is a view similar to Fig. 2, but in which the parts are shown when the compressor is idle;

Fig. 4 is an enlarged cross-sectional view taken along the line 44 of Fig. 1;

Fig. 5 is an exploded view, in perspective, of the drive shaft and the unloading means, parts being shown broken away;

Fig. 6 is an enlarged view of a portion of the mechanism under running conditions, shown in Fig. 2, but with parts broken away in a different manner to show the underlying mechanism;

Fig. 7 is a view similar to Fig. 6, but showing the positions which the parts occupy when the compressor is idle;

Fig. 8 is a vertical cross-sectional view of a portion of acompressor utilizing the slightly modified form of the unloading device;

Fig. 9 is a top plan view, with portions broken away of the mechanism shown in Fig. 8; and

Fig. 10 is a detail of a portion of the sealing ring used to seal hermetically the casing which encloses the compressor.

One embodiment of a compressor built in accordance with my invention, has a cylinder or wall, a piston or impeller, a drive shaftand an eccentric drive between the shaft and piston or impeller for causing the piston or impeller and the cylinder or wall to produce a pumping action, and, with these parts, there is provided a means or device which is responsive to starting conditions, or to reduced speed conditions, in the compressor for varying the eccentricity of the drive between the drive shaft and the piston or impeller, so that the starting load of the compressor is materially reduced during the starting period or whenever the compressor operates at a reduced speed. In this manner, it is possible to drive the compressor with a driving device which does not need to have an exception-. ally high starting torque, such as a split phase motor with the assurance that the motor will be capable of driving the compressor without stalling.

In order that the invention may be clearly understood, I have shown it applied to a compressor of the rotary type, it being understood that the illustration of my invention in connection with a rotary compressor in no way limits the scope of its usefulness, since the invention is capable of application to many other types of compressors.

In the embodiment shown in Figs. 1 to 7 inclusive, the compressor includes a casing generally designated by III, in which are placed a motor H and compressing mechanism driven by the motor, which includes a stationary, circular wall, or cylinder I! with which a piston or impeller l3 cooperates. The piston or impeller l3 preferabiy includes a circular or cylindrical portion depending from a plate H which rides on top of the stationary plate IS in which the wall or cylinder I2 is cut. The impeller l3 cooperates with the wall I? to produce a pumping action, and, to this end, it is given a rotary or gyratory motion within the wall l2, so that it causes the pumping chamber IE to rotate or follow a path from the edge ll of the divider block l8, around the wall l2, finally terminating in the other edge I 9 of the divider block I8. An intake opening 20 is provided adjacent the edge ll, so that refrigerant, or other fluid, may enter the space between the wall or cylinder l2 and the piston or impeller l3, this fluid being forced by the rotary or gyratory movement through the pumping chamber it against the edge IQ of the impeller block I8, from whence the refrigerant or fluid passes upward y through an opening 2| in the plate it past the valve 22 and into the space 23 of the casing H]. A suitable discharge opening is provided in the casing l0 so that the compressed refrigerant or fluid may be discharged to the required place. In this particular embodiment, the compressed refrigerant passes through passages in the mechanism to the space 24 of the casing Ill and is then discharged through the opening 25 to the pipe 26 which leads to a condenser 21, from whence the condensed refrigerant is discharged nto, a receiver 28. The liquid refrigerant is then expanded through a suitable expansion device 29 and enters the evapo rator 3|] from whence the evaporated refrigerant is returned by the pipe 3| past the check valve 32 to the intake passage 20.

The compressor may be single acting or it may be double acting, and in this particular embodiment it has been shown as a double acting rotary compressor. To this end a second wall or cylinder is provided inside of the impeller or piston l3. -This wall also may be a stationary circular or cylindrical wall and the impeller may be provided with a circular rotary or gyratory wall 3| which cooperates with the wall 30' to form an interior pumping chamber 32 similar to the chamber IE, but removed therefrom by .an arc of 180.

The chamber 32 is fed by the extension 33 of the intake opening 20 which extension is cut through the impeller l3 and leads to a place adjacent to the edge ll of the impeller I8. The plate I4 is provided with an opening 34, similar to the opening 2|, leading to the top of the plate on which is placed a valve 35 past which the refrigerant compressed in chamber 32 is discharged into the space 23.

The particular compressing mechanism above described may be taken to be typical of any compressing mechanism to which my unloader may be connected. The unloader is such that it provides a maximum eccentric drive between the shaft and the impeller when the compressor has attained a predetermined or normal speed and which varies this eccentricity when the compressor stops or is not running at the normal speedor a speed slower than the predetermined speed. In, this particular embodiment, a drive shaft 40 is provided which has an eccentric drive between said shaft and the piston or impeller I3, the main axis of the shaft 40 being indicated at 402, Fig. 5. This eccentric drive may include eccentric extension 4| of reduced diameter which has an axis 42. A further reduced extension 43 is placed on the extension 4| for a purpose more fully to be described. An eccentric sleeve 44 fits rotatably over the extension 4| and this sleeve 44 has an external diameter eccentric with its internal diameter as clearly shown in Fig. 5 and the external diameter of sleeve 44 has its axis at 441:. The total maximum eccentricity produced by the eccentricity of extension M and the sleeve 44 is the distance between the axis 401: and 44m, and

. this is the eccentricity required to maintain the piston and the cylinder of the compressor in pumping cooperation. A suitable bearing is provided between the sleeve 44 and the impeller l3. Preferablythis bearing is formed by the annular ball bearing race 45 which, being truly annular,

does not change the eccentricity established by the extension 4| and the sleeve 44. When the extension 4| and sleeve 44 occupy the relative angular position indicated in Figs. 1, 2, 4, 5, and 6 they produce the maximum eccentricity required; but when the extension 4| is rotated relf ativel to sleeve 44 so that they occupy positions indicated in Figs. 3.and '7 their composite eccentricity is reduced, so that the pumping efficiency of the compressor during the starting mechanism, although it is to be understood that any function ofthe starting condition of the compressor or its driving member may be utilized to produce this relative rotational movement. In this particular embodiment, a centrifugal device actuates sleeve 44, so that the sleeve 44 has its maximum eccentricity in alignment with the maximum' eccentricity of the extension 4| when the compressor is at normal speed. This is accomplished by means of one or more weights 41 which occupy an extended position at full speed and which are retracted by spring means 41a: or

the like when the compressor stops or runs at a sub-normal speed. A pair of weights 41 are provided with slots 48 which cooperate with pins 49 formed on the extension 50 of the sleeve 44. When the compressor is at full speed, the pins 49 are held at positions corresponding to the maximum eccentric position and when the weights 41 are retracted the pins are rotated relatively to tension 43 and keyed therein by the key 54. The

holes 53 are equally distant from the axis 40.2:of the main portion of the shaft 40;. so that when the weights 41 are at their extended position, they are statically balanced, since they. rotate about the main axis 40x, and this static balance is maintained also during starting conditions since the weights tend to occupy symmetrical positions about the axis 401 throughout the starting period. In view of this, the unloader is balanced at all speeds. v

The motor may be connected to the shaft 40 in any suitable manner but preferably is connected by attaching the rotor 60 to the shaft 40,

the rotor being driven by the stator 6| mountedin the portion 62 of the casing iii. The compressed refrigerant in the space 23 passes through the. ball race 46 and through the openings 63 into the space 24 and is discharged through opening 25 as heretofore described. Lubricant is placed in the compressor and normally occupies the lower portion of the casing l0. It passes through the screen 64 and through the opening 65 into the sump 66.- The thread 61 on the shaft 40 acts as a pump and lifts the lubricant to the radial opening 68 from whence the lubricant is forced through the central bore 69 and is discharged through the opening l0 on top of the compressor so as to maintain a body of lubricant in the space 23 and thus insure a proper sealing of the compressor. A radial opening 1| permits a portion of the lubricant to pass to the spiral groove 12 in order to lubricate the bearing 13.

The casing I0 is hermetically sealed by any suitable means, which may include a copper wire 14, originally cylindrical in cross-section, which is formed into a ring by telescoping the ends of the wire as at Ma shown in Fig. 10, this joint being properly soldered before the ring is placed in the casing ill. The top 15 of the casing l0 is'bolt ed down onto the copper ring by means of bolts 16 as will be apparent from the drawings. A similar joint, if necessary, is provided in the lower portion of the casing.

In the modification shown in Figs. 8 and 9, a single weight is used. To this end the shaft 40 is provided with an eccentric extension 4| on which is mounted the eccentric sleeve 44'. The sleeve 44' is provided with a plate having'a vertical extension 8| through which the arm 82 of the weight 83 slidingly passes. An anchor 84 provided with a hook 85 pivotally holds the inner end of the arm 82 and is firmly held by means of the bolt 86 onto the shaft 48. A spring 81 is connected at one end to the plate 88 which is keyed with the hook 85 to the shaft 48' and has its other end connected to the extension 8|. It will be noted that the weight 83 is forced by the spring 81 so as to reduce the eccentricity and that the weight 83 flies out and produces the normal or maximum eccentricity when the motor assumes its normal speed, substantially in the same manner in which correspondingly numbered parts operate in Figs. 1 to 7.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understoodthat other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A compressor comprising a stationary hori- -zontal cylinder plate having an annular groove therein provided with fluid inlet and outlet ports forming a pumping chamber, a piston plate resting on said cylinder plate for sliding engagement therewith and having a pumping ring extending into said groove, said ring being of less diameter than said groove and having a slot therein, a divider block passing through said slot and positioned between said inlet and outlet ports and having cylindricai'ends which have bearingin arcuate recesses in the side walls of said groove in said cylinder plate and having straight sides cooperating-with said slot in said ring, a shaft having an eccentric portion'on which portion said piston plate is rotatably mounted, the said eccentric portion being drivingly connected to said piston plate to cause gyration thereof within said pumping chamber, means for rotating said shaft, means biasing said pumping ring into concentric relationship with said groove when the compressor is at rest or at low operating speeds, and centrifugal means for overcoming said biasing means and increasing the eccentricity of said eccentric the inlet and the outlet means, a shaft havingan eccentric portion on which portion said pumping ring is rotatably mounted, the said eccentric portion being drivingly connected to said pumping ring to cause gyration thereof within said pumping chamber, means for rotating said shaft, means biasing said pumping ring into substantially concentric relationship with said chamber when the compressor is at rest or at low operating speeds, and centrifugal means for overcoming said biasing means and increasing the eccentricity of said eccentric portion when the speed of said compressor exceeds a predetermined limit whereby said ring will be brought into pumping engagement with said pumping chamber.

3. In a rotary compressor, means forming an annular pumping chamber, inlet and outlet means for said chamber, a pumping ring of less diameter than said chamber located within said chamber, means between said inlet and outlet means cooperating with said pumping ring and the walls of said pumping chamber so as to completely close off the pumping chamber between the inlet and the outlet means, a shaft having an eccentric portion on which portion said pumping ring is rotatably mounted, the said eccentric portion being drivingly connected to said pumping ring to cause gyration thereof within said pumping chamber, means for rotating said shaft, means carried by said shaft biasing said pumping ring into substantially concentric relationship with said chamber when the compressor is at rest or at low operating speeds, and centrifugal means carried by said shaft for overcoming said biasing means and increasing the eccentricity of said eccentric portion when the speed of said compressorexceeds a predetermined limit whereby said ring will be brought into pumping engagement with said pumping chamber.

4. A rotary compressor comprising means forming a cylinder having a cylindrical wall, inlet and outlet ports for said cylinder, a divider block between said ports, a cylindrical piston of less diameter than said cylinder, means for position ing said piston in varying eccentric relation within said cylinder, means including a driving shaft on which said piston is mounted whereby the axis of said piston is caused to revolve about a cen- -ter within the cylindrical wall of said cylinder,

means for maintaining the piston in substantially concentric relation with said cylinder wall when the piston is stationary, and speed responsive means for moving said piston into varying eccentric relation with said cylindrical wall in accordance with the speedof said shaft.

ANDREW A. KUCHER. 

